Julia, a woman suffering from a degenerative sight disease, finds her twin sister Sara, who has already gone as a result of the same disease, hanged in the basement of her house.Everything points to suicide, but Julia is compelled to investigate what she intuitively feels is a murder case. Determined to retrace her sister's final steps, she is drawn into a maze of hidden threats and spiralling dread - a dark world that seems to hide a mysterious, malevolent presence. As Julia begins to uncover clues to the truth of her sister's death, she is convinced that someone is watching her - someone who means her terrible harm. Those close to her begin to disappear and then to die. Her sight gone, confined to her sister's house, Julia finds herself trapped in a nightmare from which she cannot awake. Will she survive?